1. Field of the Invention
The present invention refers to an innovative lubricated chain equipped with innovative lubricant sealing gaskets.
2. State of the Prior Art
So called “O-Ring” chains, are widely used in the field of motorcycling, but not only, thanks to their very high durability, obtained by using O-ring gaskets, which allow the grease to be kept between pin and insert, so that the chain has a greater wear resistance than any non O-Ring chain.
Unfortunately, O-Ring chains also have to be lubricated periodically.
The reason for this is to be found in the need of keeping a correct lubrication, not only between pin and insert, but also between insert and roller.
Especially at high speeds, indeed, it may be the case that the lubricant between roller and insert is lost due to the centrifugal force. This fact causes overheating of the contact surface between roller and insert and their wearing. This wearing is the main cause of the breaking of the rollers and the heating spreading to the pin-insert articulation, accelerates the degradation of the grease sealed therein and the subsequent wearing of the pin and insert. If an O-Ring chain is not lubricated periodically, these two phenomena substantially limit its useful life.
In order to avoid this problem, attempts have been made in the past, to seal the grease between insert and roller as well. Chains with rollers, which are externally shaped in proximity to the ends, so as to accommodate sealing rings, made to work between the external surface of the roller and the side plate, have thus been proposed. However, in such chains the sealing rings are exposed and can easily deteriorate whilst the chain is operating. For example, the O-Ring risks coming into contact with the gear wheels on which the chain is engaged. The hydraulic seal is poor, due to the fact that there are only two pivot points of the gasket. Not being protected, the O-Ring needs to be lubricated and thus all the substantial advantage of the solution is lost. Chains having such a structure, if used in the motorcycling field, have a warrantee of less than 1000 Km.
Moreover, in order to maintain the size of the engagement surfaces of the rollers (foreseen by law), it is necessary to increase the thickness of the chain.
Chains with a step seat at each internal end of the roller have also been proposed, for example, in U.S. Pat. No. 5,425,679. The ring gasket is inserted in each rectangular seat thus formed. The gasket is thus protected from the outside. However, the durability of such chains is still unsatisfactory if a periodic lubrication is not carried out. A first cause can be due to the degradation of the seal caused by mechanical actions both resulting from the forces and also from the contact points, which are produced on the O-Ring within the rectangular seat. The chain is also difficult to assemble automatically or semi-automatically, since it is difficult to fill the interfaces with lubricant and then to position the sealing gaskets. This makes the chain excessively expensive.
Also in the industrial field there are a series of applications where it is not possible to carry out a periodic lubrication of the chain and, in the case of O-Ring chains, they start to encounter difficulties due to the rollers, especially in environments which are highly corrosive.
The general purpose of the present invention is to avoid the aforementioned drawbacks by providing a chain which does not require lubricating and that is long lasting.